The attached document from the RI census gives a different date of birth, and the 1920 census says that Donald immigrated in 1903 and Hannah in 1909.
Also, it's fairly common for record keepers to interpret 'yyyy' as '01-01-yyyy' so she was not necessarily born on 1 January of whatever year she was born.
She also seems to have got her parish of birth confused.
So the best that can be said from the information found so far is that Hannah was born some time around 1880-1883, most probably in Ayrshire.
This is the description of Snodgrass from
https://scotlandsplaces.gov.ukSNODGRASS; Authority for spelling Robert Dunlop. (Tenant), John Stewart. Bartonholm, Robert Blair. Eglinton Iron Works. Kilwinning. A Good Farm Ho [House] & out offices Occupied by the Tenant, under Earl of Eglinton. the Proprietor.See it on the map at
https://maps.nls.uk/geo/explore/#zoom=16.0&lat=55.63372&lon=-4.70591&layers=257&b=1&marker=55.62809,-4.70969 - beside the River Garnock, which is the boundary between the parish of Irvine and the parish of Neilston. It has been completely obliterated by later developments.
There are no obvious records of (H)ann(a)(h) McNeilage in either the births index or the census indexes. So we need to look for less obvious ones. For example, could Hannah have been illegitimate and registered under a different surname? Could she in fact have been born somewhere else and brought to Snodgrass before she was old enough to know? Why did she think Snodgrass was in the parish of Kilwinning? The law required all births to be registered, and if Hannah's was not, why not?
So many questions, so few answers